American Gothic: Gloomy atmosphere plays a smaller role in American Gothic, psychic breakdown plays a role.
Cthulhu: A universe created by author H.P. Lovecraft a fictional premise was that the world was once inhabited by another more ancient race of dark powers.
Cross Genre: Horror stories that ofter cross genre lines, to fantasy, science, romance, etc
Cutting Edge: ideas in fiction that refuses archetypal, supernatural aspects that are new.
Dark Fantasy: a fantasy story that can have supernatural elements but is not the supernatural fiction of traditional vampires, werewolves, etc.
Dark Fiction: a term often used by Horror creators that see the word "Horror" as a not-friendly marketing term.
English Gothic: Horror stories that developed as a reaction to the Age of Reason and dominated English literature from 1764 into the early 19th century.
Erotic Horror: Usually "erotic" in this sense means sensual sexual content integral to the story and can be as mild as "romantic suspense" or as hard as "pornographic".
Extreme: Horror that goes straight to the blood-and-guts and aims for the gross-out without hesitation.
Fantastique: a borrowed French word meaning Fantastic Fiction or fiction that has some "super-natural" element to it. Also the title of a good genre news magazine.
Future noir: Noir type stories that take place in the near future
Goth: Short term for Gothic
Horrorists: individual who studies, collects and enjoys aspects of Horror fiction
Interstitial Fiction: Horror stories that defy genre breakdowns
Lovecraftian: Name for the style of story telling that followed after the author H.P. Lovecraft had past.
Mixed Genre: see Cross Genre or Slipstream
Neo-noir: Noir type stories that take place in present day
Noir: Usually set in an urban underworld of crime and moral ambiguity. Dark, cynical, paranoid themes of corruption, alienation, lust, obsession, violence, revenge and the difficulty finding redemption in non perfect world.
Noir SF: Noir type stories that take place in far future
Psychological Horror: Based on the disturbed human psyche. Psychological horror can also deal with ambiguous reality and seem to be supernatural.
Quiet (or Soft) Horror: Subtle, never visceral or too shocking, with atmosphere and mood providing the miasma of fear rather than graphic description.
Slipstream: Another expression of "Cross Genre" Horror stories that often cross genre lines, to fantasy, science, romance, etc
Splat: Lots of gore, variation of Extreme or Splatter
Splatter: Lots of gore, variation of Extreme or Splat Horror
Splatterpunk: Near future horror that involves technological advances in killing
Surreal: Not really sub-generic, it can be used just to mean unreal; strange or bizarre.
Tech-noir: Noir type stories that take place in a mixed history, usually Technology is the cause of this advanced story telling style which harkens back to icons of past eras.
Visceral: A term, not a sub-genre, that refers to earthier, more reality-based or supernatural fiction with a tendency to be "in-your-face" but not to extreme.
Weird: "Weird fiction" is sometimes used as a synonym for horror. It can also mean only strange, uncanny, supernatural stories or refer to a school of writing popularized by the pulp magazine "Weird Tales" more "traditional" horror.